Secondary Non-Specific Defences Flashcards
What is an antigen-presenting cell?
A cell that isolates the antigen from a pathogen and places it on the plasma membrane so that it can be recognised by other cells in the immune system.
What is clonal selection?
Selection of a specific B or T cell that is specific to the antigen.
What is cytokinesis?
Hormone-like molecules used in cell signalling to stimulate the immune response.
What is a neutrophil?
A type of white blood cell that engulfs foreign matter and traps it in a large vacuole (phagosome), which fuses with lysosomes to digest the foreign matter.
What are opsonins?
Proteins that bind to the antigen on a pathogen and then allow phagocytes to bind.
When are secondary defences used?
Secondary defences are used to combat pathogens that have entered the body.
What are antigens?
Chemical markers on the outer membrane of a pathogen which the body uses to recognise that it is foreign.
What are opsonins a type of?
Antibody
What is the role of the opsonin?
To enhance the ability of phagocytic cells to bind and engulf the pathogen.
What id the first line of secondary defence?
Phagocytosis
What are neutrophils?
They are the most common type of phagocyte.
Where are neutrophils made?
In the bone marrow.
What do neutrophils do?
They engulf and digest pathogens.
What is pus?
The collection of dead neutrophils that contain bacteria.
What are macrophages?
Play an important role in initiating the specific responses to invading pathogens.
What do macrophages travel in the blood as?
Monocytes
What happens when a macrophage engulfs a pathogen?
It does not fully digest it. Instead the antigen from the surface of the pathogen is saved and moved to a special protein complex on the surface of the cell.
What is the macrophage called once it has kept the antibody on the surface of it’s membrane?
An antigen-presenting cell.
Why is a special protein complex needed by the macrophages?
So that it doesn’t get recognised as foreign and start getting attacked by other phagocytes.
What is the role of antigen-presenting cells?
To increase the chance that the antigen will come into contact with them.
